In motion picture photography using an interlaced video camera, in order to realize smooth motion without increasing data rate and to reduce flickering, an interlaced scan in which a single-frame image is divided into a top field and a bottom field every other line, each field is scanned in a horizontal direction, and 50 to 60 fields per second are transmitted, for example, is generally carried out for the motion picture photography. Encoding methods for a video signal in the interlaced structure photographed as above (hereinafter referred to as “interlaced image”) include an encoding method for encoding individual interlaced images in each field (hereinafter referred to as “field-based encoding”), and an encoding method for encoding a non-interlaced image synthesized by two sequential interlaced images for each frame (hereinafter referred to as “frame-based encoding”).
Since the interlaced image in each field has skipped scanning lines, pixel correlation in a vertical direction is weaker than that of the non-interlaced image synthesized by two sequential interlaced images for each frame with a continuous scanning line. Therefore, in view of compression efficiency, the frame-based encoding is typically more advantageous than the field-based encoding.